System and method for analog beamforming for single-connected antenna array

ABSTRACT

A method and system analog beamforming for a single-connected antenna array is herein disclosed. A method includes estimating analog channels on a per-antenna basis, calculating explicitly an analog beamforming matrix based on the estimated analog channels, and performing analog beamforming based on the calculated analog beamforming matrix.

PRIORITY

This application is based on and claims priority under 35 U.S.C. §119(e) to a U.S. Provisional Patent Application filed on Nov. 21, 2018in the United States Patent and Trademark Office and assigned Ser. No.62/770,492, the entire contents of which are incorporated herein byreference.

FIELD

The present disclosure relates generally to communication systems. Inparticular, the present disclosure relates to a method and system foranalog beamforming for a single-connected antenna array.

BACKGROUND

In a millimeter wave area, single-connection antenna arrays are ofinterest, meaning that each antenna is only equipped with one phaseshifter and analog antennas are separated into several groups, eachgroup is combined independently into separated RF chains, instead offull-connection antenna arrays, that each RF chain has full access toall analog antennas and each analog antenna are connected with multiplephase shifters.

A typical implementation for analog beamforming uses an exhaustivesearch method to select a beamforming vector from a given codebook. Sucha search method, however, does not guarantee optimality.

SUMMARY

According to one embodiment, a method for analog beamforming for asingle-connected antenna array includes estimating analog channels on aper-antenna basis, calculating explicitly an analog beamforming matrixbased on the estimated analog channels, and performing analogbeamforming based on the calculated analog beamforming matrix.

According to one embodiment, a system for analog beamforming for asingle-connected antenna array includes a transceiver and a processorconfigured to estimate analog channels on a per-antenna basis, calculateexplicitly an analog beamforming matrix based on the estimated analogchannels, and perform analog beamforming based on the calculated analogbeamforming matrix.

According to one embodiment, a method for analog beamforming for asingle-connected antenna array includes calculating explicitly an analogbeamforming matrix, estimating analog channels based on virtual antenna,and performing analog beamforming based on the calculated analogbeamforming matrix and the estimated channels on virtual antennas.

According to one embodiment, a system for analog beamforming for asingle-connected antenna array includes a transceiver and a processorconfigured to calculate explicitly an analog beamforming matrix,estimate analog channels based on virtual antenna, and perform analogbeamforming based on the calculated analog beamforming matrix and theestimated channels on virtual antennas.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram of a channel recovery process, according to anembodiment;

FIG. 2 is a diagram of a channel recovery process, according to anembodiment; and

FIG. 3 is a block diagram of an electronic device in a networkenvironment, according to one embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are described indetail with reference to the accompanying drawings. It should be notedthat the same elements will be designated by the same reference numeralsalthough they are shown in different drawings. In the followingdescription, specific details such as detailed configurations andcomponents are merely provided to assist with the overall understandingof the embodiments of the present disclosure. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein may be made withoutdeparting from the scope of the present disclosure. In addition,descriptions of well-known functions and constructions are omitted forclarity and conciseness. The terms described below are terms defined inconsideration of the functions in the present disclosure, and may bedifferent according to users, intentions of the users, or customs.Therefore, the definitions of the terms should be determined based onthe contents throughout this specification.

The present disclosure may have various modifications and variousembodiments, among which embodiments are described below in detail withreference to the accompanying drawings. However, it should be understoodthat the present disclosure is not limited to the embodiments, butincludes all modifications, equivalents, and alternatives within thescope of the present disclosure.

Although the terms including an ordinal number such as first, second,etc. may be used for describing various elements, the structuralelements are not restricted by the terms. The terms are only used todistinguish one element from another element. For example, withoutdeparting from the scope of the present disclosure, a first structuralelement may be referred to as a second structural element. Similarly,the second structural element may also be referred to as the firststructural element. As used herein, the term “and/or” includes any andall combinations of one or more associated items.

The terms used herein are merely used to describe various embodiments ofthe present disclosure but are not intended to limit the presentdisclosure. Singular forms are intended to include plural forms unlessthe context clearly indicates otherwise. In the present disclosure, itshould be understood that the terms “include” or “have” indicateexistence of a feature, a number, a step, an operation, a structuralelement, parts, or a combination thereof, and do not exclude theexistence or probability of the addition of one or more other features,numerals, steps, operations, structural elements, parts, or combinationsthereof.

Unless defined differently, all terms used herein have the same meaningsas those understood by a person skilled in the art to which the presentdisclosure belongs. Terms such as those defined in a generally useddictionary are to be interpreted to have the same meanings as thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the present disclosure.

The electronic device according to one embodiment may be one of varioustypes of electronic devices. The electronic devices may include, forexample, a portable communication device (e.g., a smart phone), acomputer, a portable multimedia device, a portable medical device, acamera, a wearable device, or a home appliance. According to oneembodiment of the disclosure, an electronic device is not limited tothose described above.

The terms used in the present disclosure are not intended to limit thepresent disclosure but are intended to include various changes,equivalents, or replacements for a corresponding embodiment. With regardto the descriptions of the accompanying drawings, similar referencenumerals may be used to refer to similar or related elements. A singularform of a noun corresponding to an item may include one or more of thethings, unless the relevant context clearly indicates otherwise. As usedherein, each of such phrases as “A or B,” “at least one of A and B,” “atleast one of A or B,” “A, B, or C,” “at least one of A, B, and C,” and“at least one of A, B, or C,” may include all possible combinations ofthe items enumerated together in a corresponding one of the phrases. Asused herein, terms such as “1^(st),” “2nd,” “first,” and “second” may beused to distinguish a corresponding component from another component,but are not intended to limit the components in other aspects (e.g.,importance or order). It is intended that if an element (e.g., a firstelement) is referred to, with or without the term “operatively” or“communicatively”, as “coupled with,” “coupled to,” “connected with,” or“connected to” another element (e.g., a second element), it indicatesthat the element may be coupled with the other element directly (e.g.,wiredly), wirelessly, or via a third element.

As used herein, the term “module” may include a unit implemented inhardware, software, or firmware, and may interchangeably be used withother terms, for example, “logic,” “logic block,” “part,” and“circuitry.” A module may be a single integral component, or a minimumunit or part thereof, adapted to perform one or more functions. Forexample, according to one embodiment, a module may be implemented in aform of an application-specific integrated circuit (ASIC).

The systems and methods disclosed herein are targeted at improvinganalog beamforming by using an explicitly calculated beamforming vectorbased on a single connected antenna array. Channel information on analogantennas are required for explicit calculation. Disclosed herein aremultiple channel recovery methods to estimate the channel information onanalog antennas.

Referring to the system model in Equation (1):y=W ^(H) Hx+W ^(H) n  (1)

where y is the received signal, W is the beamforming matrix, and n isthe noise. The transmitter analog beamforming and precoder matrices areabsorbed in an effective channel matrix, H. The dimensions for eachparameter are specified with the variables below:

W: N_(RX)×N_(RF);

H: N_(RX)×N_(s);

y: N_(RF)×1;

x: N_(s)×1;

n: N_(RF)×1; with

N_(s): the number of streams (e.g., 2);

N_(RF): the number of RF chains (e.g., 2);

N_(RX,RF): the number of received analog antennas per RF chain (e.g.,4); and

N_(RX)=N_(RX,RF)*N_(RF): the number of total received analog antennas(e.g., 8).

In particular, the receiver analog beamforming matrix, W, is the maindesign parameter to derive. The following calculations were made in thecase where there are 2 Rx panels, each panel has 4 antennas such thatN_(RF)=2 and N_(RX,RF)=4. To accommodate the practical RF constraints, Wis a form of block diagonal matrix, having two column beamforming matrixvectors, w₁ and w₂, each of which has the dimension N_(RX,RF)×1 andcorresponds to the first and second RF chain. W may be written as inEquation (2):

$\begin{matrix}{W = \begin{bmatrix}w_{1} & 0 \\0 & w_{2}\end{bmatrix}} & (2)\end{matrix}$

To overcome the channel covariance matrix

${R = {{HH}^{H} = \begin{bmatrix}R_{a} & R_{b} \\R_{c} & R_{d}\end{bmatrix}}},$Equations (3) and (4) are used as follows:(ŵ ₁ ,ŵ ₂)=arg max log g(w ₁ ,w ₂)  (3)

$\begin{matrix}{{g\left( {w_{1},w_{2}} \right)} = {{{\sigma^{2}I} + {{\begin{bmatrix}w_{1} & 0 \\0 & w_{2}\end{bmatrix}^{H}\begin{bmatrix}R_{a} & R_{b} \\R_{c} & R_{d}\end{bmatrix}}\begin{bmatrix}w_{1} & 0 \\0 & w_{2}\end{bmatrix}}}}} & (4)\end{matrix}$

with Equation (4) being the indication function.

The beamforming matrix W and/or beamforming vectors w₁, w₂ can beexplicitly calculated via an iterative single-connection analogbeamforming (ISAB) process, where phase shifter coefficients areobtained sequentially (e.g., take an initial value for w₁, then use w₁to calculate w₂, and with the new w₂, calculate a new w₁, calculate anew w₂ with the new w₁, and so forth), or via an eigen-basedsingle-connection analog beamforming (ESAB) process.

The closed form solution for the single-connection beamforming problemis derived with a few approximations in the ESAB process. Channelinformation on analog antennas are used for the explicit calculationanalog beamforming method (both ISAB and ESAB) of the presentdisclosure. However, the available receiver (Rx) side channelinformation is the estimated channel on each RF chain based on channelstate information reference signal (CSI-RS) beam-sweeping periods.

Regarding the ISAB process, the ISAB process is derived assuming anarrow-band channel (or single subcarrier case). Given an initial valueof w₂, the problem is formulated to Equation (5):max log(g(w ₁ |w ₂))  (5)

such that, in Equation (6):ŵ ₁(w ₂)=arg max w ₁ ^(H) D ₁ w ₁=Q ₁(:,1)  (6)

where, in Equation (7):D ₁ =R _(a)(w ₂ ^(H) R _(d) w ₂+σ²)−R _(b) w ₂ w ₂ ^(H) R _(b) ^(H) =Q₁Λ₁ Q ₁ ^(H)  (7)

Updating with given w₁ is similar, as in Equation (8):ŵ ₂(ŵ ₁)=arg max w ₂ ^(H) D ₂ w ₂=arg max w ₂ ^(H) Q ₂Λ₂ Q ₂ ^(H) w ₂=Q ₂(:,1)  (8)

with Equation (9):D ₂ =R _(d)(ŵ ₁ ^(H) R _(a) ŵ ₁+σ²)−R _(c) ŵ ₁ ŵ ₁ ^(H) R _(c) ^(H) =Q₂Λ₂ Q ₂ ^(H)  (9)

Multiple CSI-RS resource elements (REs) exist over the whole bandwidthpart. When applying the ISAB method, the D1 and D2 matrix is computedfor each subcarrier and then they are averaged across subcarriers.D_(i,n) represents the D_(i) matrix calculated on the nth subcarrier, asin Equation (10):

$\begin{matrix}{D_{i} = {\frac{1}{N}{\sum\limits_{n}D_{i,n}}}} & (10)\end{matrix}$

However, the above-described solutions may not consider the constraintof amplitude in analog beamforming. To satisfy this constraint, thephase information is taken as Equation (11) and Equation (12):w ₂ =e ^(j∠w) ²   (11)w ₁ =e ^(j∠w) ¹   (12)

Regarding the ESAB process, the ESAB process is, in general, asuboptimum solution, and is a closed form solution for the initialoptimization problem in Equation (3) with the following threeassumptions:

(1) The signal-to-noise ratio (SNR) is high enough so that noise isignored (i.e., σ²≈0);

(2) The amplitude constraint in the design of analog beamforming isignored at the derivation procedure (i.e., w*₁D₁w₁≈λ_(max)) under theassumption its effects are minor; and

(3) Two streams are transmitted over multiple antennas.

Similar to ISAB, ESAB is also derived assuming a narrow-band channel(e.g., a single subcarrier case). The channel matrix is defined as

$H = \begin{bmatrix}h_{11} & h_{12} \\h_{21} & h_{22}\end{bmatrix}$and K=h*₂₂ h₁₁ ^(H)−h*₂₁h₁₂ ^(H), such that, as in Equation (13):

$\begin{matrix}{{\overset{\sim}{D}}_{2} = {{{{\begin{bmatrix}h_{22}^{*} & h_{21}^{*}\end{bmatrix}\begin{bmatrix}h_{11}^{H} \\{- h_{12}^{H}}\end{bmatrix}}\begin{bmatrix}h_{11} & {- h_{12}}\end{bmatrix}}\begin{bmatrix}h_{22}^{T} \\h_{21}^{T}\end{bmatrix}} = {{KK}^{H} = {{\overset{\sim}{Q}}_{2}\Lambda_{2}{\overset{\sim}{Q}}_{2}^{H}}}}} & (13)\end{matrix}$

Using the high SNR approximation and ignoring noise, the optimalsolution is w₂={tilde over (Q)}₂ ^(H)(:,1) and w₁={tilde over (Q)}₁(:,1)with Equation (14):{tilde over (D)} ₁ =K ^(H) w* ₂ w ₂ ^(T) K={tilde over (Q)} ₁{tilde over(Λ)}₁ {tilde over (Q)} ₁ ^(H)  (14)

For the single subcarrier case, w₁=1/βK^(H)w*₂, where β is thenormalization factor. For multi subcarrier cases, {tilde over (D)}_(i,n)is defined as the {tilde over (D)}_(i) matrix calculated on the nthsubcarrier, such that in Equation (15):

$\begin{matrix}{{\overset{\sim}{D}}_{i} = {\frac{1}{N}{\sum\limits_{n}{\overset{\sim}{D}}_{i,n}}}} & (15)\end{matrix}$

Similar to ISAB, to satisfy the constraint of analog beamforming, thephase information of w₂ and w₁ can be taken.

In the present ISAB/ESAB processes, the channel matrix per each analogantenna is assumed to be known. In reality, directly estimating thechannel per analog antenna may not be possible. Instead, the beamformedchannel in each CSI-RS symbol can be estimated during beam sweeping.

In addition to the ISAB/ESAB processes above, multiple processes forrecovering analog channels are provided herein.

FIG. 1 is a diagram 100 of a channel recovery process, according to anembodiment. The channel recovery process 100 involves an analogbeamforming procedure based on per-antenna channel estimation (CE). Theprocess utilizes the signal 102 and a beam sweeping pilot signal 104. At106, the process performs the digital channel estimation on the pilot104. At 108, the process performs the analog channel estimation.

Assuming the channel vector between the i^(th) Rx panel and the j^(th)Tx panel on subcarrier k does not change during the Rx beam sweepingduration, on the l^(th) sweeping symbol, beam forming vector a_(l) isapplied on the i^(th) Rx panel. l=1, . . . , N where N is the totalnumber of beam sweeping symbols, as in Equation (16):r _(i,j,k,l) =a _(l) ^(H) h _(i,j,k)  (16)

By defining r_(i,j,k)=[r_(i,j,k,1), r_(i,j,k,2), . . . r_(i,j,k,N)]^(T)and A=[a₁, a₂, . . . , a_(N)]^(H), Equation (17) is presented as:r _(i,j,k) =Ah _(i,j,k)  (17)

The analog channel estimation 108 is an under deterministic problem,especially when the beam-sweeping duration is not long enough to recoverall the channel information per panel and has many solutions, such asleast square estimation and compress sensing. Regularized least square(RLS) channel recovery may be utilized in the analog channel estimation108.

Assuming noise is completely eliminated via de-noising, the channelvector for the i^(th) Rx panel and the j^(th) Tx panel on subcarrier kcan be recovered from a least square method as in Equation (18):h _(i,j,k) =A ^(H)(AA ^(H))⁻¹ r _(i,j,k)  (18)

The dimension of r_(i,j,k) is N×1, A is N×N_(RX,RF), h_(i,j,k) isN_(RX,RF)×1. In practical applications, it is likely that N≤N_(RX,RF),which causes an ill-condition on the least square. Instead, theregularized least square imposes another constraint that the channelpower does not diverge, as in Equation (19):L(h _(i,j),λ)=∥r _(i,j,k) −Ah _(i,j,k)∥² +λ∥h _(i,j,k)∥²  (19)

Equation (19) is converted to an original least square problem, as inEquation (20):

$\begin{matrix}{{L\left( {h_{i,j,k},\lambda} \right)} = {{\begin{bmatrix}r_{i,j,k} \\0\end{bmatrix} - {\begin{bmatrix}A \\\sqrt{\lambda}\end{bmatrix}h_{i,j,k}}}}^{2}} & (20)\end{matrix}$

Thus, the RLS solution may be provided as Equation (21):h _(i,j,k) =A ^(H)(AA ^(H) +λI _(N))⁻¹ r _(i,j,k)  (21)

Then, at 110, the process performs the ISAB or ESAB as described above,and at 112, the process performs analog beamforming.

FIG. 2 is a diagram of a channel recovery process 200, according to anembodiment. The channel recovery process 200 is an analog beamformingprocedure without per-antenna CE, such that the explicit calculationanalog beamforming process (ISAB/ESAB) are performed first on theestimated channel on each RF chain, and then a post processing functionis applied to the beamforming vectors from the ISAB/ESAB.

The process 200 utilizes a signal 202 and a beam sweeping pilot signal204. At 206, the process 200 performs digital channel estimation on thepilot 204, and then performs the ISAB or ESAB as described above at 208.

At 210, processing on a virtual antenna occurs. This is anotheralternative solution to recover a channel vector, h_(i,j,k), from anoise model of Equation (22):r _(i,j,k) =A(h _(i,j,k)+{acute over (δ)}_(k))  (22)

This process does not technically recover a channel vector h_(i,j,k),but instead takes into account Ah_(i,j,k) as a virtual channel. As aresult, the received signal is re-written as Equation (23):r _(i,j,k) ={tilde over (h)} _(i,j,k) +A{acute over (δ)} _(k)  (23)

Additionally, the noise can be pre-whitened, such as in Equation (24):{tilde over (r)} _(i,j,k) =R _(C) ^(−1/2) r _(i,j,k)==R _(C) ^(−1/2) +{tilde over (h)} _(i,j,k)+{hacek over (δ)}_(k)  (24)

where, as in Equation (25):R _(C)=σ² AA ^(H)  (25)

Now, R_(C) ^(−1/2){tilde over (h)}_(i,j,k) serves as an effectivechannel and is used to generate the average covariance of channels overall subcarriers.

It is assumed that the resulting solution from ISAB or ESAB would beW_(B), as in Equation (26):W _(B) =f _(ABF)({tilde over (r)} _(i,j,k) ,A)  (26)

where f_(ABF)(⋅) is the analog beamforming function such as ISAB orESAB. W_(B) is not restricted by the amplitude constraint. It isgenerated from f_(ABF)(⋅) without eliminating the amplitude information.As a result, the amplitude of each element in W_(B) is not necessarily1.

Thereafter, the virtual channel is used to derive the beam coefficientvector as Equation (27):W _(B) =f _(ABF)({tilde over (r)} _(i,j,k) ,A)  (27)

The channel covariance matrix may be averaged in a frequency domain overall subcarriers, and then D_(i) in Equation (10) is calculated once.

FIG. 3 is a block diagram of an electronic device 301 in a networkenvironment 300, according to one embodiment. Referring to FIG. 3, theelectronic device 301 in the network environment 300 may communicatewith an electronic device 302 via a first network 398 (e.g., ashort-range wireless communication network), or an electronic device 304or a server 308 via a second network 399 (e.g., a long-range wirelesscommunication network). The electronic device 301 may communicate withthe electronic device 304 via the server 308. The electronic device 301may include a processor 320, a memory 330, an input device 350, a soundoutput device 355, a display device 360, an audio module 370, a sensormodule 376, an interface 377, a haptic module 379, a camera module 380,a power management module 388, a battery 389, a communication module390, a subscriber identification module (SIM) 396, or an antenna module397. In one embodiment, at least one (e.g., the display device 360 orthe camera module 380) of the components may be omitted from theelectronic device 301, or one or more other components may be added tothe electronic device 301. In one embodiment, some of the components maybe implemented as a single integrated circuit (IC). For example, thesensor module 376 (e.g., a fingerprint sensor, an iris sensor, or anilluminance sensor) may be embedded in the display device 360 (e.g., adisplay).

The processor 320 may execute, for example, software (e.g., a program340) to control at least one other component (e.g., a hardware or asoftware component) of the electronic device 301 coupled with theprocessor 320, and may perform various data processing or computations.As at least part of the data processing or computations, the processor320 may load a command or data received from another component (e.g.,the sensor module 376 or the communication module 390) in volatilememory 332, process the command or the data stored in the volatilememory 332, and store resulting data in non-volatile memory 334. Theprocessor 320 may include a main processor 321 (e.g., a centralprocessing unit (CPU) or an application processor (AP)), and anauxiliary processor 323 (e.g., a graphics processing unit (GPU), animage signal processor (ISP), a sensor hub processor, or a communicationprocessor (CP)) that is operable independently from, or in conjunctionwith, the main processor 321. Additionally or alternatively, theauxiliary processor 323 may be adapted to consume less power than themain processor 321, or execute a particular function. The auxiliaryprocessor 323 may be implemented as being separate from, or a part of,the main processor 321.

The auxiliary processor 323 may control at least some of the functionsor states related to at least one component (e.g., the display device360, the sensor module 376, or the communication module 390) among thecomponents of the electronic device 301, instead of the main processor321 while the main processor 321 is in an inactive (e.g., sleep) state,or together with the main processor 321 while the main processor 321 isin an active state (e.g., executing an application). According to oneembodiment, the auxiliary processor 323 (e.g., an image signal processoror a communication processor) may be implemented as part of anothercomponent (e.g., the camera module 380 or the communication module 390)functionally related to the auxiliary processor 323.

The memory 330 may store various data used by at least one component(e.g., the processor 320 or the sensor module 376) of the electronicdevice 301. The various data may include, for example, software (e.g.,the program 340) and input data or output data for a command relatedthererto. The memory 330 may include the volatile memory 332 or thenon-volatile memory 334.

The program 340 may be stored in the memory 330 as software, and mayinclude, for example, an operating system (OS) 342, middleware 344, oran application 346.

The input device 350 may receive a command or data to be used by othercomponent (e.g., the processor 320) of the electronic device 301, fromthe outside (e.g., a user) of the electronic device 301. The inputdevice 350 may include, for example, a microphone, a mouse, or akeyboard.

The sound output device 355 may output sound signals to the outside ofthe electronic device 301. The sound output device 355 may include, forexample, a speaker or a receiver. The speaker may be used for generalpurposes, such as playing multimedia or recording, and the receiver maybe used for receiving an incoming call. According to one embodiment, thereceiver may be implemented as being separate from, or a part of, thespeaker.

The display device 360 may visually provide information to the outside(e.g., a user) of the electronic device 301. The display device 360 mayinclude, for example, a display, a hologram device, or a projector andcontrol circuitry to control a corresponding one of the display,hologram device, and projector. According to one embodiment, the displaydevice 360 may include touch circuitry adapted to detect a touch, orsensor circuitry (e.g., a pressure sensor) adapted to measure theintensity of force incurred by the touch.

The audio module 370 may convert a sound into an electrical signal andvice versa. According to one embodiment, the audio module 370 may obtainthe sound via the input device 350, or output the sound via the soundoutput device 355 or a headphone of an external electronic device 302directly (e.g., wiredly) or wirelessly coupled with the electronicdevice 301.

The sensor module 376 may detect an operational state (e.g., power ortemperature) of the electronic device 301 or an environmental state(e.g., a state of a user) external to the electronic device 301, andthen generate an electrical signal or data value corresponding to thedetected state. The sensor module 376 may include, for example, agesture sensor, a gyro sensor, an atmospheric pressure sensor, amagnetic sensor, an acceleration sensor, a grip sensor, a proximitysensor, a color sensor, an infrared (IR) sensor, a biometric sensor, atemperature sensor, a humidity sensor, or an illuminance sensor.

The interface 377 may support one or more specified protocols to be usedfor the electronic device 301 to be coupled with the external electronicdevice 302 directly (e.g., wiredly) or wirelessly. According to oneembodiment, the interface 377 may include, for example, a highdefinition multimedia interface (HDMI), a universal serial bus (USB)interface, a secure digital (SD) card interface, or an audio interface.

A connecting terminal 378 may include a connector via which theelectronic device 301 may be physically connected with the externalelectronic device 302. According to one embodiment, the connectingterminal 378 may include, for example, an HDMI connector, a USBconnector, an SD card connector, or an audio connector (e.g., aheadphone connector).

The haptic module 379 may convert an electrical signal into a mechanicalstimulus (e.g., a vibration or a movement) or an electrical stimuluswhich may be recognized by a user via tactile sensation or kinestheticsensation. According to one embodiment, the haptic module 379 mayinclude, for example, a motor, a piezoelectric element, or an electricalstimulator.

The camera module 380 may capture a still image or moving images.According to one embodiment, the camera module 380 may include one ormore lenses, image sensors, image signal processors, or flashes.

The power management module 388 may manage power supplied to theelectronic device 301. The power management module 388 may beimplemented as at least part of, for example, a power managementintegrated circuit (PMIC).

The battery 389 may supply power to at least one component of theelectronic device 301. According to one embodiment, the battery 389 mayinclude, for example, a primary cell which is not rechargeable, asecondary cell which is rechargeable, or a fuel cell.

The communication module 390 may support establishing a direct (e.g.,wired) communication channel or a wireless communication channel betweenthe electronic device 301 and the external electronic device (e.g., theelectronic device 302, the electronic device 304, or the server 308) andperforming communication via the established communication channel. Thecommunication module 390 may include one or more communicationprocessors that are operable independently from the processor 320 (e.g.,the AP) and supports a direct (e.g., wired) communication or a wirelesscommunication. According to one embodiment, the communication module 390may include a wireless communication module 392 (e.g., a cellularcommunication module, a short-range wireless communication module, or aglobal navigation satellite system (GNSS) communication module) or awired communication module 394 (e.g., a local area network (LAN)communication module or a power line communication (PLC) module). Acorresponding one of these communication modules may communicate withthe external electronic device via the first network 398 (e.g., ashort-range communication network, such as Bluetooth™, wireless-fidelity(Wi-Fi) direct, or a standard of the Infrared Data Association (IrDA))or the second network 399 (e.g., a long-range communication network,such as a cellular network, the Internet, or a computer network (e.g.,LAN or wide area network (WAN)). These various types of communicationmodules may be implemented as a single component (e.g., a single IC), ormay be implemented as multiple components (e.g., multiple ICs) that areseparate from each other. The wireless communication module 392 mayidentify and authenticate the electronic device 301 in a communicationnetwork, such as the first network 398 or the second network 399, usingsubscriber information (e.g., international mobile subscriber identity(IMSI)) stored in the subscriber identification module 396.

The antenna module 397 may transmit or receive a signal or power to orfrom the outside (e.g., the external electronic device) of theelectronic device 301. According to one embodiment, the antenna module397 may include one or more antennas, and, therefrom, at least oneantenna appropriate for a communication scheme used in the communicationnetwork, such as the first network 398 or the second network 399, may beselected, for example, by the communication module 390 (e.g., thewireless communication module 392). The signal or the power may then betransmitted or received between the communication module 390 and theexternal electronic device via the selected at least one antenna.

At least some of the above-described components may be mutually coupledand communicate signals (e.g., commands or data) therebetween via aninter-peripheral communication scheme (e.g., a bus, a general purposeinput and output (GPIO), a serial peripheral interface (SPI), or amobile industry processor interface (MIPI)).

According to one embodiment, commands or data may be transmitted orreceived between the electronic device 301 and the external electronicdevice 304 via the server 308 coupled with the second network 399. Eachof the electronic devices 302 and 304 may be a device of a same type as,or a different type, from the electronic device 301. All or some ofoperations to be executed at the electronic device 301 may be executedat one or more of the external electronic devices 302, 304, or 308. Forexample, if the electronic device 301 should perform a function or aservice automatically, or in response to a request from a user oranother device, the electronic device 301, instead of, or in additionto, executing the function or the service, may request the one or moreexternal electronic devices to perform at least part of the function orthe service. The one or more external electronic devices receiving therequest may perform the at least part of the function or the servicerequested, or an additional function or an additional service related tothe request, and transfer an outcome of the performing to the electronicdevice 301. The electronic device 301 may provide the outcome, with orwithout further processing of the outcome, as at least part of a replyto the request. To that end, a cloud computing, distributed computing,or client-server computing technology may be used, for example.

One embodiment may be implemented as software (e.g., the program 340)including one or more instructions that are stored in a storage medium(e.g., internal memory 336 or external memory 338) that is readable by amachine (e.g., the electronic device 301). For example, a processor ofthe electronic device 301 may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. Thus, a machine may be operated to perform at least onefunction according to the at least one instruction invoked. The one ormore instructions may include code generated by a complier or codeexecutable by an interpreter. A machine-readable storage medium may beprovided in the form of a non-transitory storage medium. The term“non-transitory” indicates that the storage medium is a tangible device,and does not include a signal (e.g., an electromagnetic wave), but thisterm does not differentiate between where data is semi-permanentlystored in the storage medium and where the data is temporarily stored inthe storage medium.

According to one embodiment, a method of the disclosure may be includedand provided in a computer program product. The computer program productmay be traded as a product between a seller and a buyer. The computerprogram product may be distributed in the form of a machine-readablestorage medium (e.g., a compact disc read only memory (CD-ROM)), or bedistributed (e.g., downloaded or uploaded) online via an applicationstore (e.g., Play Store™), or between two user devices (e.g., smartphones) directly. If distributed online, at least part of the computerprogram product may be temporarily generated or at least temporarilystored in the machine-readable storage medium, such as memory of themanufacturer's server, a server of the application store, or a relayserver.

According to one embodiment, each component (e.g., a module or aprogram) of the above-described components may include a single entityor multiple entities. One or more of the above-described components maybe omitted, or one or more other components may be added. Alternativelyor additionally, a plurality of components (e.g., modules or programs)may be integrated into a single component. In this case, the integratedcomponent may still perform one or more functions of each of theplurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. Operations performed by the module, the program, oranother component may be carried out sequentially, in parallel,repeatedly, or heuristically, or one or more of the operations may beexecuted in a different order or omitted, or one or more otheroperations may be added.

Although certain embodiments of the present disclosure have beendescribed in the detailed description of the present disclosure, thepresent disclosure may be modified in various forms without departingfrom the scope of the present disclosure. Thus, the scope of the presentdisclosure shall not be determined merely based on the describedembodiments, but rather determined based on the accompanying claims andequivalents thereto.

What is claimed is:
 1. A method for analog beamforming for asingle-connected antenna array, comprising: estimating analog channelson a per-antenna basis; calculating explicitly an analog beamformingmatrix based on the estimated analog channels according to an iterativesingle-connection analog beamforming (ISAB) process that includesobtaining a first phase shifter coefficient and obtaining a second phaseshifter coefficient based on the obtained first phase shiftercoefficient; and performing analog beamforming based on the calculatedanalog beamforming matrix.
 2. The method of claim 1, wherein estimatinganalog channels further comprises recovering analog channel informationby a regularized least square (RLS) channel recovery.
 3. A system foranalog beamforming for a single-connected antenna array, comprising: atransceiver; and a processor configured to: estimate analog channels ona per-antenna basis; calculate explicitly an analog beamforming matrixbased on the estimated analog channels according to an eigen-basedsingle-connection analog beamforming (ESAB) process that includesderiving a closed form solution for single-connection optimization; andperform analog beamforming based on the calculated analog beamformingmatrix.
 4. The system of claim 3, wherein the processor is furtherconfigured to estimate analog channels by recovering analog channelinformation by a regularized least square (RLS) channel recovery.
 5. Amethod for analog beamforming for a single-connected antenna array,comprising: calculating explicitly an analog beamforming matrix;estimating analog channels based on virtual antenna by recovering analogchannel information as a virtual channel; and performing analogbeamforming based on the calculated analog beamforming matrix and theestimated channels on virtual antennas.
 6. The method of claim 5,wherein the analog beamforming matrix is calculated according toiterative single-connection analog beamforming (ISAB) process.
 7. Themethod of claim 5, wherein the analog beamforming matrix is calculatedaccording to eigen-based single-connection analog beamforming (ESAB)process.
 8. The method of claim 7, wherein the ESAB process comprisesderiving a closed form solution for single-connection optimization.
 9. Asystem for analog beamforming for a single-connected antenna array,comprising: a transceiver; and a processor configured to: calculateexplicitly an analog beamforming matrix; estimate analog channels basedon virtual antenna by recovering analog channel information as a virtualchannel; and perform analog beamforming based on the calculated analogbeamforming matrix and the estimated channels on virtual antennas. 10.The system of claim 9, wherein the analog beamforming matrix iscalculated according to iterative single-connection analog beamforming(ISAB) process.
 11. The system of claim 10, wherein the ISAB processcomprises obtaining phase shifter coefficients sequentially.
 12. Thesystem of claim 9, wherein the analog beamforming matrix is calculatedaccording to eigen-based single-connection analog beamforming (ESAB)process.